The present invention relates to an assembly of a fan and a shroud, and more particularly, to an assembly of a fan and a shroud which is easy to manufacture and has improved structural strength and high efficiency.
In general, according to the principle of fluid dynamics, an assembly of a fan and a shroud used in a vehicle is provided with a bell-mouthed airflow guide portion on all air inflow or outflow side, so as to increase airflow volume. Such a structure is disclosed in U.S. Pat. Nos. 4,514,140 to Knopf, 4,566,852 to Hauser, 5,066,194 to Amr et al., 2,030,993 to Langenkamp et al., 3,515,498 to Tomita, 3,842,902 to Poslusny, and 5,244,347 to Gallivan et al.
The above known air guiding structures have a bell-mouthed airflow guide portion on the air inflow/outflow side so as to smoothly induce or discharge incoming or outgoing air as much as possible and accordingly to increase airflow volume.
However, since general shrouds including those of the above inventions are made of metal consisting of plural individual elements, they are difficult to assemble. Further, difficulty in adjusting assembly tolerance prevents the gap between the fan blade and shroud from being adequately maintained and therefore air leakage created via the gap between the fan and shroud cannot be positively suppressed. Meanwhile, FIG. 1 illustrates the assembly of fan 1 and shroud 2 made of synthetic resin by injection molding. Referring to FIG. 1, in order to form a bell-mouthed airflow guide portion 3, the mold assembly requires more than three sets of molding segments. Further, since the bell-mouthed airflow guide portion 3 is formed with a simple plate-shaped member without reinforcement, the airflow guide portion is subject to damage due to the low mechanical strength and to distortion due to impacts and warping.